摘要:
A compact voltage sensor with stable characteristics is provided. A measuring beam that is incident from an optical fiber is branched into first and second modulation-inducing waveguides of a wave branching/combining section within an optical integrated circuit. Phase changes of opposite sign are induced in the measuring beams propagating within the first and second modulation waveguides by applying voltages of mutually opposite sign to modulation-inducing electrodes, to induce a phase difference between the two. By reflecting the measuring beams from a reflective surface, propagating them back in the opposite direction within the first and second modulation waveguides, and passing them through the optical intensity modulation section again, thus applying a further phase modulation thereto, the phase difference between the measuring beams proceeding in the opposite direction within the first and second modulation waveguides can be made to be substantially twice the phase difference of the measuring beams before they are reflected by the reflective surface. The sensor also has a function to protect a sensor section thereof from dielectric breakdown caused by the accidental input of a high voltage.
摘要:
An electromagnetic field intensity measuring apparatus capable of measuring an electromagnetic field intensity accurately and sensitively without affection by any disturbance, including a measuring light generating section for emitting a measuring light containing first and second polarized light components which are orthogonal to each other and slightly different in frequency from each other; an optical input polarization-maintaining fiber for receiving one of the first and second polarized light components in the direction of X-axis polarization and the other polarized light component in the direction of Y-axis polarization, the optical input polarization-maintaining fiber conducting the measuring light to the electromagnetic field measuring place; a sensor section disposed in the electromagnetic field measuring place, the sensor section receiving the measuring light from the optical input polarization-maintaining fiber and modulating the phase of the incident measuring light depending on the electromagnetic field intensity; and an optical output polarization-maintaining fiber for receiving one of the first and second polarized light components from the sensor section in the direction of X-axis polarization and the other polarized light component in the direction of Y-axis polarization, the optical output polarization-maintaining fiber conducting the measuring light outside the electromagnetic field measuring place. The phase difference between the first and second polarized light components contained in the measuring light from the optical output polarization-maintaining fiber is detected to determine the electromagnetic field intensity.
摘要:
An apparatus measures the intensity of an electric field with a compact sensor equipped with a light modulater of a Mach-zender interferometer type and a condenser-type antenna. The sensor modulates coherent measuring lights propagated through branched two optical paths according to the voltage induced on the surfaces of plates of a condenser-type antenna of the sensor. The modulated lights are merged and interfered with each other and result in merged light different in intensity from the original measuring light. A waveguide-type optical integrated circuit formed in the sensor calculates the intensity of the merged light having the intensity dependent on the intensity of the magnetic field.
摘要:
A laser Doppler velocimeter in which laser light whose frequency changes continuously at least for a fixed time duration is branched into at least two beams, and the at least two branched beams are respectively transmitted by at least one pair of optical fibers having an optical path difference therebetween, and are focused onto a region to be measured by at least one focusing device. The scattered light of the laser beams focused in the region to be measured are received by a light-receiving device via at least one incident device. At least one Doppler shift frequency in the region to be measured is calculated on the basis of the frequency of a signal of the scattered light received by the light-receiving device, the optical path difference, and a rate of change of the frequency of the laser light. The flow velocity and the direction of the flow velocity are calculated from the calculated Doppler shift frequency.
摘要:
An electromagnetic field intensity measuring apparatus comprises a sensor located in the electromagnetic field measuring place for receiving the measuring light from the optical fiber, the sensor being adapted to modulate the measuring light entering the sensor depending on the intensity of the electromagnetic field, the modulated light being then re-applied to the optical fiber; a polarization rotating device located between the measuring light generating device and the optical fiber, the polarization rotation device being operative to cause the polarized wavefront of the measuring light passed therethrough to rotate a given angle in the direction of passage; and a polarization beam splitter disposed between the measuring light generating device and the polarization rotating device, the polarization beam splitter being operative to permit only the measuring light from said measuring light generating device to pass through said polarization beam splitter and also to reflect the modulated measuring light inputted through the polarization rotating device in a predetermined direction. The electromagnetic field intensity in the measuring place can be calculated, based on the amplitude of the measuring light reflected by the polarization beam splitter.
摘要:
A light-emitting device includes a light-emitting diode, a red light-emitting phosphor layer, a yellow light-emitting phosphor layer, and a blue light-emitting phosphor layer. These layers are stacked in the stacking sequence of the yellow, blue, and red phosphor layers in order of increasing distance from the LED. The stacking sequence of the yellow and blue phosphor layers is first determined in such a manner that these layers do not interact with each other. The stacking sequence of the red and yellow phosphor layers and the stacking sequence of the red and blue phosphor layers are determined by the discriminant D. This determination of the stacking sequence suppresses a reduction in the conversion efficiency of the phosphors due to concentration quenching, improving the emission efficiency of the light-emitting device.
摘要:
A light-emitting device includes a light-emitting diode, a red light-emitting phosphor layer, a yellow light-emitting phosphor layer, and a blue light-emitting phosphor layer. These layers are stacked in the stacking sequence of the yellow, blue, and red phosphor layers in order of increasing distance from the LED. The stacking sequence of the yellow and blue phosphor layers is first determined in such a manner that these layers do not interact with each other. The stacking sequence of the red and yellow phosphor layers and the stacking sequence of the red and blue phosphor layers are determined by the discriminant D. This determination of the stacking sequence suppresses a reduction in the conversion efficiency of the phosphors due to concentration quenching, improving the emission efficiency of the light-emitting device.
摘要:
A light source comprising a light emitting diode comprising a GaN-based compound and having a single quantum well structure, and a driving voltage source for applying a pulse voltage to the light emitting diode, wherein a voltage at a low level of the pulse voltage is set to a voltage lower than a voltage at which a fall time of the light emitting diode is made the longest.
摘要:
A light source comprising a light emitting diode comprising a GaN-based compound and having a single quantum well structure, and a driving voltage source for applying a pulse voltage to the light emitting diode, wherein a voltage at a low level of the pulse voltage is set to a voltage lower than a voltage at which a fall time of the light emitting diode is made the longest.
摘要:
The invention provides a GaN green LED drive device comprising: a bias current output unit for outputting a pulse-like bias current having a low level higher by a predetermined value than a zero level; and a peaking unit for peaking the bias current outputted from the bias current output unit to make rise of the bias current higher than a high level and make fall of the bias current lower than the low level to thereby obtain a peaked bias current supplied to a GaN green LED. The bias current is peaked while the low level of the bias current is set at a higher value (10 mA) than that in the related art. Hence, the fall time tf becomes 6.6 nsec. The fall time tf can be shortened greatly compared with that in the related art.